1. Field of the Invention
The present invention relates to a connector assembly, more particularly to a connector assembly capable of transmitting optical signal.
2. Description of Related Art
Recently, personal computers (PC) are used of a variety of techniques for providing input and output. Universal Serial Bus (USB) is a serial bus standard to the PC architecture with a focus on computer telephony interface, consumer and productivity applications. The design of USB is standardized by the USB Implementers Forum (USB-IF), an industry standard body incorporating leading companies from the computer and electronic industries. USB can connect peripherals such as mouse devices, keyboards, PDAs, gamepads and joysticks, scanners, digital cameras, printers, external storage, networking components, etc. For many devices such as scanners and digital cameras, USB has become the standard connection method.
USB supports three data rates: 1) A Low Speed rate of up to 1.5 Mbit/s (187.5 KB/s) that is mostly used for Human Interface Devices (HID) such as keyboards, mice, and joysticks; 2) A Full Speed rate of up to 12 Mbit/s (1.5 MB/s). Full Speed was the fastest rate before the USB 2.0 specification and many devices fall back to Full Speed. Full Speed devices divide the USB bandwidth between them in a first-come first-served basis and it is not uncommon to run out of bandwidth with several isochronous devices. All USB Hubs support Full Speed; 3) A Hi-Speed rate of up to 480 Mbit/s (60 MB/s). Though Hi-Speed devices are advertised as “up to 480 Mbit/s”, not all USB 2.0 devices are Hi-Speed. Hi-Speed devices typically only operate at half of the full theoretical (60 MB/s) data throughput rate. Most Hi-Speed USB devices typically operate at much slower speeds, often about 3 MB/s overall, sometimes up to 10-20 MB/s. A data transmission rate at 20 MB/s is sufficient for some but not all applications. However, under a circumstance transmitting an audio or video file, which is always up to hundreds MB, even to 1 or 2 GB, currently transmission rate of USB is not sufficient. As a consequence, faster serial-bus interfaces are being introduced to address different requirements. PCI Express, at 2.5 GB/s, and SATA, at 1.5 GB/s and 3.0 GB/s, are two examples of High-Speed serial bus interfaces.
From an electrical standpoint, the higher data transfer rates of the non-USB protocols discussed above are highly desirable for certain applications. However, these non-USB protocols are not used as broadly as USB protocols. Many portable devices are equipped with USB connectors other than these non-USB connectors. One important reason is that these non-USB connectors contain a greater number of signal pins than an existing USB connector and are physically larger as well. For example, while the PCI Express is useful for its higher possible data rates, a 26-pin connectors and wider card-like form factor limit the use of Express Cards. For another example, SATA uses two connectors, one 7-pin connector for signals and another 15-pin connector for power. In essence, SATA is more useful for internal storage expansion than for external peripherals.
The existing USB connectors have a small size but low transmission rate, while other non-USB connectors (PCI Express, SATA, et al) have a high transmission rate but large size. Neither of them is desirable to implement modern high-speed, miniaturized electronic devices and peripherals. To provide a kind of connector with a small size and a high transmission rate for portability and high data transmitting efficiency is much more desirable.
In recent years, more and more electronic devices are adopted for optical data transmission. It may be a good idea to design a connector which is capable of transmitting an electrical signal and an optical signal. Design concepts are already common for such a type of connector which is compatible of electrical and optical signal transmission. The connector includes metallic contacts assembled to an insulated housing and several optical lenses bundled together and mounted to the housing also. A kind of hybrid cable includes wires and optical fibers that are respectively attached to the metallic contacts and the optical lenses.
For example, CN Pub. Pat. No. 101345358 published on Jan. 14, 2009 discloses an optical USB connector which has a fiber device added to a USB connector. The fiber device includes a number of optical lenses and several fibers respectively connected to the lenses. Thus, the optical USB connector can transmit electrical signals and optical signals. However, optical lenses are unable to being floatable with regard to the housing, and they are not accurately and aligned with and optically coupled to counterparts, if there are some errors in manufacturing process.
U.S. Pat. No. 7,896,559 issued on Mar. 1, 2011 to Yi et al. discloses a cable assembly having floatable termination. The cable assembly includes an insulative housing with a base portion and tongue portion projecting forwardly from the base portion, a mounting cavity defined in the tongue portion; a plurality of contacts supported by the base portion, each contact having a mating portion arranged proximate to the top side of the tongue portion, and a tail portion extending beyond a back surface of the base portion; an optical module accommodated in the mounting cavity and a spring member arranged between the optical module and a back side of the mounting cavity to urge the optical module forwardly.
Yi's device has proposed a solution to solve the aforementioned problem by adding one spring member located behind and constantly urging the optical module which is capable of moving with regarding to the insulative housing. However, the optical module may tilt when move on the insulative housing. It is desirable to provide an improved cable assembly with an optical module capable of moving on a corresponding insulative housing more stable or balanceable so as to ensure proper mating with its counterpart.